Heat exchanger with condensate collector



Oct. 19, 1965 R. M. HERBERT 3,212,288

HEAT EXCHANGER WITH GONDENSATE COLLECTOR Filed March 24, 1961 2 Sheets-Sheet 1 CONDENSER T0 DRAIN 4e BLOWER HEATING UNIT INVENTOR. RICHARD M. HERBERT Oct. 19, 1965 R. M HERBERT 3,212,288

HEAT EXCHANGER WITH CONDENSATE COLLECTOR Filed March 24, 1961 2 Sheets-Shet 2 INVENTOR. mm M. Hansen BY l'i MM, VJ 2 am ATTYS United States Patent 3,212,288 HEAT EXCHANGER WITH CONDENSATE COLLECTOR Richard M. Herbert, Nashville, Tenn, assignor to Heil Quaker Corporation, Nashville, Tenn., a corporation of Delaware Filed Mar. 24, 1961, Ser. No. 98,077 8 Claims. (Cl. 62290) The invention relates to heat exchangers generally and more particularly to heat exchangers of the fin and tube type.

The invention is especially well suited for transferring heat to or from air or other circulating gases and it has for its primary object the provision of a heat exchanger which imposes a minimum of resistance to air flow therethrough for a given area of heat exchange surface. A related object is to provide a heat exchanger which is extremely compact in relation to its effective heat exchange surface area and which is well adapted for combination usage with conventional central heating equipment.

Another object is to provide a heat exchanger of the above general character which is easy to fabricate, inexpensive to assemble and in which all enclosed parts are readily accessible for cleaning for service without requiring removal from the equipment with which it is associated.

Another object is to provide a heat exchanger equipped with a simple header for connecting a series of coils which is also operative as an accumulator efiective to insure complete flooding of the coils.

It is also an object of the invention to provide a heat exchanger which permits a substantial reduction in the amount of insulating material required in the enclosing housing structure.

Other objects and advantages of the invention will become apparent from the following detailed description of the preferred embodiment illustrated in the accompanying drawings in which FIGURE 1 is an end view of a heat exchanger embodying the features of the invention shown as installed to operate in a conventional forced air heating system.

FIG. 2 is a side view of the heat exchanger with parts of the enclosing housing structure and associated ducts broken away.

FIG. 3 is a fragmentary end view of one of the coil units of the heat exchanger showing the relationship of the drain pan to the other elements of the unit.

FIG. 4 is a fragmentary view though one of the coil units taken in offset planes substantially on the line 44 of FIG. 1.

While a preferred form of the invention has been shown together with its application to a particular type of forced air heating system, it is not intended to limit the invention to details of construction of the illustrated embodiment or to the application to or installation in any specific type of air treating system. The intention is to cover all modifications and adaptations of the heat exchanger as well as its adaptation to use in other types of systems falling within the spirit and scope of the invention as more broadly or generally characterized in the appended claims.

For purposes of illustration, a heat exchanger embodying the invention has been shown in the form of an assembly comprising two fin and tube units 10 enclosed in a generally rectangular sheet metal housing 11. The housing 11 is open at the top and bottom to define a channel for the flow of air through the assembly. The particular housing and assembly illustrated is well suited for use in conjunction with a conventional forced air heating system to convert that system for summer cooling without interfering with its winter heating function.

A conventional forced air heating system has been diagrammatically shown in FIG. 1 as including a source of heat such as a furnace 15 connected to deliver heated air to a plenum chamber 16 from which it is distributed to the space to be heated through a series of ducts 17. A motor driven blower 18 forces air circulation through the system withdrawing air from the space to be heated through a cold air or return duct 19 and discharging it into the heating area of the furnace by way of a duct 20.

The furnace 15 may be of any suitable type, that shown comprising an outer sheet metal shell or bonnet 21 with an air outlet opening 22 in its top wall. The duct 20 from the blower is connected to discharge cold air near the bottom of the bonnet and the air is heated as it passes upwardly over an inner shell 23 which encloses and is heated by a heating unit 24. The heating unit 24 may be of any preferred type.

When incorporated in a heating system such as that shown in FIG. 1, the heat exchanger housing 11 is installed so as to define an air passage between the furnace outlet opening 22 and the plenum chamber 16. The air circulated by the furnace fan 18 is thus directed through the coil units 10 assembled in the housing. While ordinarily a refrigerating liquid or gas will be supplied to the coils to extract heat from the air, it will be understood that the process could be reversed if desired to supply heat to the air.

To accommodate the foregoing operation the coil units 10 are constructed in a novel manner which makes them easy to fabricate and simple to assemble. A more important consideration, however, is that the novel coil unit construction and assembly results in a heat exchanger that imposes substantially less resistance to air flow than conventional heat exchangers having comparable areas'of effective heat exchange surface.

The coil units 10 are alike, each comprising a plurality of thin fiat sheet metal fins 30 (FIGS. 2 and 4) assembled face-to-face in spaced parallel relation between similarly shaped end plates 31 of somewhat heavier gauge. The fins and plates are formed with uniformly spaced and alined holes for the reception of refrigerant conducting coils 32. The coils 32 are sinuous, presenting a series of straight sections or runs connected by return bends 33 to form a continuous tubular conduit.

In the initial assembly of a coil unit, the straight runs of the coils, which may constitute sections of tubing of appropriate length, are inserted through the holes in the fins and end plates 31 with their ends projecting outwardly beyond the respective end plates. The fins and end plates may be soldered or otherwise attached to the coils if desired to improve heat conducting efficiency. The projecting ends of adjacent tube sections alternating at opposite ends of the coil unit are then connected by the return bends 33 which preferably comprise U-shaped fittings. Thus, the tube sections and fittings form a continuous tubular passage or sinuous coil, and, in the exemplary embodiment, the open ends of each coil are presented at the same end of the unit constituting respectively an inlet to and an outlet from the coil.

In the particular coil units illustrated, tube sections and their connecting fittings 33 provide three parallel passages or coils for each unit. The coils, of course, wind back and forth between the ends of the unit, each coil of the exemplary embodiment having twelve straight runs passing through the stack of fins. It will be understood that the number of coils per unit may be increased or d creased and likewise the overall length of the coils and the number of runs may be varied depending upon the capacity required for the unit.

In carrying out the invention, the fins 30 and end plates 31 are shaped to permit a highly advantageous arrangement of the coil units in the assembly. More particularly, the fins and end plates are cut or stamped into the shape of rhomboids, thus producing a finished coil unit in the general form of a parallelepiped. The angles between the adjacent sides of the rhomboids may vary somewhat from those shown as determined by the width and height requirements of the complete heat exchanger assembly. When minimum resistance to air flow through the unit is desired, the angles are related to coil spacing so that the corresponding runs of the coils are alined in common vertical planes when the units are assembled and disposed in the position in which the assembly is intended to operate.

As indicated heretofore, the coil assembly for the heat exchanger utilizes two of the coil units 10. The units are assembled in oppositely inclined relation with their corresponding ends in abutting relation as shown in FIG. 1. The units thus present an inverted V-sha-ped form with the straight runs or coil sections adjacent the abutting ends presented in upright parallel rows spaced apart similarly to the spacing of the coil runs of the individual units. Thus, the assembly presents a substantially uniform coil spacing throughout its entire area and eliminates both the gap in coil spacing at the apex of the assembly and the shielding of a portion of the coils at the lower end of the assembly inherent in heat exchangers constructed of conventional coil units having rectangular fins. Furthermore, the terminal ends of the coils of the two units may be connected by the fittings 33 of the same dimensions as those utilized in connecting the straight runs of the units themselves. Such connections serve to join the coils of the two units into a single long tubular passage or coil with an inlet at the lower end of one coil unit and an outlet at the lower end of the other coil unit.

When the heat exchanger is to be used for cooling, the coils of the assembly may be connected individually to a source of fluid refrigerant, either gas or liquid, such as a condenser 35, forming a part of a conventional refrigerating system. While the connections may include the usual expansion valve or orifice, it has been found preferable to effect the connection through the medium of capillary tubing 36. In the exemplary embodiment, one of the capillary tubes is connected to the inlet end of each coil and the group of tubes is carried to a common fitting 37 adapted for convenient connection with a supply conduit 38 from the condenser.

The outlets for the coils of the assembled units, in this instance, open into a common header 40 effective in the exemplary heat exchanger to return spent gaseous refrigerant through a suction line 41 to the compressor 39 of the refrigerating system. The compressor, herein shown as driven by a motor M, compresses the gaseous refrigerant and delivers it to the condenser 35 where the heat is dissipated and the refrigerant liquefied in well known manner. The header 40, as will be seen by reference to FIG. 1, is disposed in a generally upright position to enable it to serve as an accumulator for trapping any liquid refrigerant passing through the coils. The coils may therefore be operated in a flooded or partly flooded condition without danger of delivering slugs of liquid to the compressor.

Heat exchangers when used for cooling air collect substantial quantities of moisture on the coils. The heat exchanger constructed in accordance with the invention includes means for collecting and disposing of such moisture. This means comprises drip pans 45 positioned below the respective coil units to receive the water dripping from the units. A suitable pipe or conduit 46 connected to the drain pans carries the collected water away to a drain or other disposal point.

The moisture collecting on the coils and fins 30 tends to run down the lower edges of the fins and drip from the lowest point of the coil unit. The novel shape of the coil units provided by the present invention is highly advantageous in reducing the width required for the drip pans 45 since the upright edges of the fins at the lower ends of the unit do not overhang as in the case of rectangular fins. There is therefore less shielding of the tubes at the lower ends of the units and the inner edged pans may be spaced farther apart to increase the air inlet area of the heat exchanger. This correspondingly decreases the resistance imposed to air flow through the units and exposes all of the coil runs to air flow, thereby making full use of the entire coil surface. Since the outer lower edges of the fins 30 and the end plates 31 are cut at an angle such that they extend vertically with the units in operating position the drippings from the fins and end plates are confined to the relatively narrow area presented by the pans.

To catch any dripping from the return bends of the coils, that is, from the fittings 33, the end plates 31 are formed with outwardly extending flanges 47 having their marginal edge portions bent up as at 47' to define inclined troughs positioned to underlie the fittings as shown in FIG. 2. The troughs extend down into the drip pans 45 to conduct collected water to the pans. It will be noted on reference to FIG. 3 that the lower edge of the conduit 46 is located a substantial distance above the end of the flange 47. The flange thus extends into the water collected in the pan which forms an effective seal to prevent fiow of untreated air around the end of the coil unit.

While the coil assembly constructed in accordance with the invention is self-supporting and may be mounted on ledges or the like in a conventional duet, the invention provides an improved support for the assembly. For this purpose, the drain pans 45 are formed on or secured to the lower edges of a pair of bafiie members 48 supported in depending relation from the side walls of the housing 11. In the preferred form shown, each baffie member comprises a sheet metal panel of substantially the dimensions of a side wall of the housing 11 with its upper marginal edge bent into the form of a locking channel 49. The locking channel is adapted to engage over a Z-shaped bracket 50 welded or otherwise rigidly secured to the side walls of the housing adjacent their upper ends. The brackets thus support the baflles inwardly of the side walls of the housing, thereby providing an insulating air space which prevents undue cooling of and condensation of moisture on the housing walls. In practice, the front wall of the housing may be hinged or mounted for convenient removal so that the baflie members and the coil assembly, which may be secured to the baflles as by screws or bolts 49', may be inserted in or withdrawn from the housing by sliding the channels endwise of the brackets.

The front and back walls of the housing 11 are preferably lined with sheets of suitable insulating material 51 to prevent excessive cooling of the walls and the condensation of moisture thereon. To confine the air flow to the active coil areas, that is, the areas between the end plates 31, the flanges 47 of the end plates are dimensioned to bring their outer edge portions into sealing engagement with the insulating material 51 as shown in FIG. 4. The flanges thus serve not only as moisture collectors but also as partitions for preventing any of the circulating air from bypassing the coil units. The side walls of the housing above the brackets 50 are desirably insulated with strips 51' of insulating material to prevent condensation on the adjacent wall areas.

The numerous advantages afforded by the construction above described will be readily apparent. To summarize briefly, it will be evident that the coil units utilize simple parts which are easy and inexpensive to fabricate. The fins 30, for example, can be produced by a simple stamping operation and since they are all alike, die costs are reduced to a minimum. Fabrication of the end plates 31 is also simple since they are alike, except for right and left hand turning of the drain trough flanges 47. The simple character of the parts of the coil units greatly facilitates assembly so that the finished heat exchanger can be produced efiiciently at relatively low cost.

The major advantage of the improved construction, however, resides in the reduction of resistance opposed to air flow through the heat exchanger for a given area of heat exchange surface. This is due in part to the reduction on the overhang of the coil units at their lower ends by reason of the unique rhomboid shape of the fins and the parallelepiped form of complete units. The elimination of this overhang confines the moisture dripping from the units to a relatively narrow area and consequently narrow drip pans can be employed. As a result, the effective area of the inlet opening to the coil units is substantially increased as compared to coil units of comparable heat exchange area constructed in the conventional manner.

The improved coil assembly can be accommodated in a simple housing 11. The provision of the bafiles for carrying the drip pans and supporting the coil assembly, as well as for shielding the sides of the housing from contact with cold air, is particularly advantageous and makes it unnecessary to line the side walls of the housing with insulating material. Also, the removable mounting of one end wall of the housing makes it easy to install or remove the coil assembly and additionally provides convenient access to the interior of the assembly so that it can be cleaned or serviced without requiring its removal from the housing.

I claim as my invention:

1. A heat exchange unit comprising, in combination, a pair of coil units assembled in oppositely inclined abutting relation to define an inverted V-shaped structure, each of said units comprising a plurality of rhomboid shaped sheet metal fins disposed in spaced parallel relation, a plurality of sinuous coils presenting a plurality of straight run connected by return bends, said straight coil runs extending through alined holes in said fins, the runs of the respective coils being oflfset relative to each other so that the terminal runs of each coil are disposed in a row parallel to the end edges of the fins and adapted to lie in a vertical row when the two units are assembled, and return bend fittings connecting the adjacent terminal ends of the coils of the respective units to form continuous coils extending through both units and with the straight runs of the coils uniformly spaced apart through the assembled units.

2. A heat exchanger comprising in combination, a pair of coil units assembled in oppositely inclined relation to define an inverted V-shaped assembly, each of said units comprising a plurality of elongated sinuous coils assembled with and extending back and forth through a plurality of rhomboid shaped sheet metal fins arranged in spaced parallel relation, said fins having their adjacent side edges disposed at an angle such that the sides of the respective fins at the apex of said structure meet in a vertical plane and the opposite sides of said fins terminate in a vertical plane at opposite sides of the assembly to present a minimum area from which moisture can drip, and means defining narrow drain pans receiving the lower ends of the units to catch moisture dripping from the fins.

3. A heat exchanger comprising, in combination, a pair of coil units assembled in oppositely inclined relation to define an inverted V-shaped structure, each .of said coil units comprising a plurality of rhomboid shaped sheet metal fins disposed in spaced parallel relation, a plurality of sinuous coils extending back and forth through aligned holes in said fins, said fins having their edges at the tip of each unit disposed at an angle to their lower edges so that the tip edges of the respective units meet in a vertical plane, and a narrow drain pan receiving the lower end of each unit to catch moisture dripping from said fins, said fins having their edges at the lower end of the unit disposed at an angle to said lower edges so as to terminate in a vertical plane and 6 thereby minimize the overhang from which moisture can drip whereby the width required for the drain pan is substantially reduced.

4. A heat exchanger comprising, in combination, a pair of coil units assembled in oppositely inclined relation to define an inverted V-shaped assembly, each of said units comprising a plurality of rhomboid shaped sheet metal fins disposed in spaced parallel relation, the adjacent sides of said fins being disposed at an angle such that corresponding sides of the fins of the respective units meet in a vertical plane at the apex of said assembly, a plurality of elongated sinuous coils extending back and forth through aligned holes in said fins, the end runs of the coils of each unit being disposed in a substantially vertical row in the assembled structure, couplings connecting the ends of corresponding coils at the adjacent sides of the respective units to produce continuous coils extending through both units, a generally upright header connecting the open ends of the coils of one of the units, a refrigerant supply conduit and tubing connecting the open ends of the coils of the other unit to said refrigerant supply conduit.

5. A heat exchanger comprising, in combination, a pair of coil units assembled in oppositely inclined relation to define an inverted V-shaped assembly, each of said coil units including end plates with integral trough shaped flanges extending outwardly from its lower edge, a housing having front. rear and side walls enclosing said assembly, a pair of sheet metal panels having means for supporting the respective units adjacent their lower ends, cooperating means on said side Walls operative to support said assembly on said housing and to prevent air from bypassing the assembly along the side walls, and sheets of insulating material lining the front and back walls of said housing, said flanges sealingly engaging the inner faces of said sheets to prevent air from bypassing the assembly along the front and rear walls of the housing.

6. A heat exchanger comprising, in combination, a pair of coil units assembled in oppositely inclined relation to define an inverted V-shaped assembly, each of said units comprising a plurality of rhomboid shaped sheet metal fins disposed in spaced parallel relation, the adjacent sides of said fins being disposed at an angle such that corresponding sides of the fins of the respective units meet in a vertical plane at the apex of said assembly, a plurality of elongated sinuous coils extending back and forth through aligned holes in said fins defining straight runs between the outer fins of each unit with U-shaped connections disposed outwardly of outer fins connecting certain of said runs, the angles between said sides of the fins and the spacing of said straight coil runs being related so that said straight runs are disposed in a series of parallel vertical planes uniformly spaced apart transversely of the assembly whereby to impose a minimum of resistance to air flow through the assembly.

7. A heat exchanger comprising, in combination, a pair of coil units assembled in oppositely inclined abutting relation to define an inverted V-shaped assembly, each of said units comprising a plurality of rhomboid shaped sheet metal fins, a plurality of sinuous coils passing through said fins defining straight runs of said coils, the spacing of said straight coil runs being related so that said straight runs are disposed in a series of parallel vertical planes uniformly spaced apart transversely of the assembly to impose a minimum of resistance to air flow through the assembly, a housing having front, rear and side walls for enclosing said assembly, a pair of sheet metal panels adapted to be supported in depending relation from the side walls of the housing, drip pans carried by the lower ends of said panels to catch moisture dripping from the units, said drip pans receiving the lower ends of the respective units to provide support therefor, and cooperating means on said panels and on the side walls of the housing for supporting the panels 7 and the assembly on said housing with the panels spaced from said side walls so as to insulate the walls from the coils.

8. A heat exchanger comprising, in combination, a pair of coil units assembled in oppositely inclined relation to define an inverted V-shaped structure, each of said coil units comprising a plurality of rhomboid shaped sheet metal fins, a pair of end plates, said fins disposed in spaced parallel relation between said end plates, a plurality of sinuous coils presenting a plurality of straight runs connected by return bends, said straight coil runs extending through aligned holes in said fins and said end plates, said return bends being located outwardly of said end plates, the angles between adjacent sides of said fins and plates being such that the upper and lower end edges of the fins and plates are disposed in vertical planes in the coil assembly, front and rear walls for enclosing said structure, each of said walls being parallel to and spaced from its respective end plates, narrow drip pans receiving the lower ends of the coil units, trough shaped flanges formed on the lower edges of the end plates positioned to underlie said return bends to intercept moisture dripping therefrom and direct the same into said drip pans and said flanges being in engagement with said walls and extending into said drip pans to effect a seal preventing How of air around the end of said units.

References Cited by the Examiner UNITED STATES PATENTS Trane 165-68 Krackowizer 165-135 X Dreier 62-288 Dixon 165-129 Henderson 62-290. Rimbach 165-124 Loveley 62-285 Hood et al. 165-48 Bungas 165-64 Crider 62-285 Switzerland.

Examiners. 

1. A HEAT EXCHANGE UNIT COMPRISING, IN COMBINATION, A PAIR OF COIL UNITS ASSEMBLED IN OPPOSITELY INCLINED ABUTTING RELATION TO DEFINE AN INVERTED V-SHAPED STRUCTURE, EACH OF SAID UNITS COMPRISING A PLURALITY OF RHOMBOID SHAPED SHEET METAL FINS DISPOSED IN SPACED PARALLEL RELATION, A PLURALITY OF SINUOUS COILS PRESENTING A PLURALITY OF STRAIGHT RUN CONNECTED BY RETURN BENDS, SAID STRAIGHT COIL RUNS EXTENDING THROUGH ALINED HOLES IN SAID FINS, THE RUNS OF THE RESPECTIVE COILS BEING OFFSET RELATIVE TO EACH OTHER SO THAT THE TERMINAL RUNS OF EACH COIL ARE DISPOSED IN A ROW PARALLEL TO THE END EDGES OF THE FINS AND ADAPTED TO LIE IN A VERTICAL ROW WHEN THE TWO UNITS ARE ASSEMBLED AND RETURN BEND FITTINGS CONNECTING THE ADJACENT TERMINAL ENDS OF THE COILS OF THE RESPECTIVE UNITS TO FORM CONTINUOUS COILS EXTENDING THROUGH BOTH UNITS AND WITH THE STRAIGHT RUNS OF THE COILS UNIFORMLY SPACED APART THROUGH THE ASSEMBLED UNITS. 